Single-pole magnet emerges in frozen concoction

Experiment simulates long-sought magnetic particle

NORTH POLE An artificial monopole (left), whose magnetic field spreads away in all directions, came from researchers’ manipulation of an ultracold gas. In a traditional bar magnet (right), the magnetic field juts out from the north pole and bends toward the south pole.

M. Atarod, adapted from M.W. Ray et al/Nature 2014

Somewhere lurking in the universe, most physicists agree, are minuscule magnets with just one pole — a north or a south, but not both. Scientists haven’t spotted any yet, but a new experiment offers an unprecedented glimpse at what these elusive magnetic particles should look like.

“It provides a window into the physics of the particle without having the particle itself in front of you,” says David Hall, the physicist at Amherst College in Massachusetts who led the research.

Magnets seem to come in only one variety, with two poles like a bar magnet’s. But in 1931, Nobel-prize winning physicist Paul Dirac demonstrated mathematically that single-pole magnets, known as monopoles, could exist. His mathematical reasoning was so strong that most physicists today have little doubt of monopoles’ existence, despite decades of fruitless searches for them at CERN and other leading institutions.

Hall had rarely thought about monopoles until

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